The operation principle of air compressor is drawing in air from the environments, compressing the air drawn in by cylinders and pistons or the like, and pumping the compressed air out through conduits. Due to the humidity of air, the compressed air may be full of air particles. Since air compressors usually use oil as lubricant, the compressed air inevitably has some oil particles included therein. The liquid particles will affect nothing, if an air compressor is used to pump air only. On the other hand, if the pressurized air is used to operate an elaborate pneumatic equipment, such as a pneumatic manipulator, the liquid particles will damage the equipment.
One way to obviate the above problem is to use dryers to reduce the humidity of air in the place where an air compressor is installed. This, however, is not a successful method. It is more common to add a single-layer-filter to the downstream conduit to remove water particles from air streams. This method is much cheaper than using dryers to dry atmosphere air. However, it is not possible to remove oil particles very well with only one filter layer.
It is therefore the object of the present invention to provide a filtering device for better removing liquid particles from air streams of air compressors which comprise a housing with an open side of which the interior is partitioned into three successive compartments, a lid which seals the housing, two filter layers which are constituted by a perforated plate and a filter sheet made of suitable filtration material, and a vane-type impeller which is rotated by the pressurized air from an air compressor to help moving the air through the layers so that the water particles and oil particles can be more effectively removed to provide a cleaner pressurized air to pneumatic equipments.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with accompanying drawings, in which